commit 134eda00e9ec4f4a2798d64b3105331f8281aba6
author Richard Henderson <richard.henderson@linaro.org> Wed Sep 23 15:00:13 2020 -0700
committer Richard Henderson <richard.henderson@linaro.org> Sun May 16 07:13:51 2021 -0500
tree afdda6327ad95d1ce5c7d1d058054d199ca55a70
parent 9793c1e224a30252dfa7ca3c1f7a5c4827ca4cfc

softfloat: Add float_cmask and constants

Testing more than one class at a time is better done with masks.
This reduces the static branch count.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

fpu/softfloat.c

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index ee4b507..64edb23 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -469,6 +469,20 @@
     float_class_snan,
 } FloatClass;
 
+#define float_cmask(bit)  (1u << (bit))
+
+enum {
+    float_cmask_zero    = float_cmask(float_class_zero),
+    float_cmask_normal  = float_cmask(float_class_normal),
+    float_cmask_inf     = float_cmask(float_class_inf),
+    float_cmask_qnan    = float_cmask(float_class_qnan),
+    float_cmask_snan    = float_cmask(float_class_snan),
+
+    float_cmask_infzero = float_cmask_zero | float_cmask_inf,
+    float_cmask_anynan  = float_cmask_qnan | float_cmask_snan,
+};
+
+
 /* Simple helpers for checking if, or what kind of, NaN we have */
 static inline __attribute__((unused)) bool is_nan(FloatClass c)
 {
@@ -1338,26 +1352,28 @@
 static FloatParts muladd_floats(FloatParts a, FloatParts b, FloatParts c,
                                 int flags, float_status *s)
 {
-    bool inf_zero = ((1 << a.cls) | (1 << b.cls)) ==
-                    ((1 << float_class_inf) | (1 << float_class_zero));
-    bool p_sign;
+    bool inf_zero, p_sign;
     bool sign_flip = flags & float_muladd_negate_result;
     FloatClass p_class;
     uint64_t hi, lo;
     int p_exp;
+    int ab_mask, abc_mask;
+
+    ab_mask = float_cmask(a.cls) | float_cmask(b.cls);
+    abc_mask = float_cmask(c.cls) | ab_mask;
+    inf_zero = ab_mask == float_cmask_infzero;
 
     /* It is implementation-defined whether the cases of (0,inf,qnan)
      * and (inf,0,qnan) raise InvalidOperation or not (and what QNaN
      * they return if they do), so we have to hand this information
      * off to the target-specific pick-a-NaN routine.
      */
-    if (is_nan(a.cls) || is_nan(b.cls) || is_nan(c.cls)) {
+    if (unlikely(abc_mask & float_cmask_anynan)) {
         return pick_nan_muladd(a, b, c, inf_zero, s);
     }
 
     if (inf_zero) {
         float_raise(float_flag_invalid, s);
-        s->float_exception_flags |= float_flag_invalid;
         return parts_default_nan(s);
     }
 
@@ -1371,9 +1387,9 @@
         p_sign ^= 1;
     }
 
-    if (a.cls == float_class_inf || b.cls == float_class_inf) {
+    if (ab_mask & float_cmask_inf) {
         p_class = float_class_inf;
-    } else if (a.cls == float_class_zero || b.cls == float_class_zero) {
+    } else if (ab_mask & float_cmask_zero) {
         p_class = float_class_zero;
     } else {
         p_class = float_class_normal;